This invention relates generally to dispensers and, more particularly, to a dispenser system for two-part epoxy adhesives and the like.
Epoxy adhesives are highly versatile and are effective in a variety of applications. Such adhesives, as a rule, are supplied in two parts ("resin" and "hardener") that must be mixed together immediately before use. The need to keep the two pans separate until immediately before use complicates the packaging for epoxy adhesives. Similarly, the need to measure and mix the two parts in equal volumes makes the use of epoxy adhesives somewhat more inconvenient than ready-to-use, one-part adhesives. For these reasons, a variety of systems and methods have been proposed for packaging two-pan epoxy adhesives.
In one well-known system, the resin and hardener parts of the epoxy are packaged in separate squeeze tubes. The user is expected to squeeze equal amounts of the resin and hardener onto a suitable mixing surface, gauging the proper ratio more or less by eye. Although capable of producing an effective adhesive, this system has a number of drawbacks. First, because two separate tubes are provided, it is possible for one of the tubes to become misplaced or otherwise lost. In this event, the remaining tube is of little use or value. Furthermore, because the proper ratio must be gauged by eye, a certain degree of skill and care is needed to ensure that the proper proportions of resin and hardener are obtained. Even relatively minor errors in the ratio of resin to hardener can compromise the strength of the final bond. Finally, when the usable portion of the epoxy adhesive has been consumed, there still remains some unmixed and uncured resin and hardener in the respective resin and hardener tubes. These tubes should not be disposed of in a landfill because it is possible for the uncured resin and hardener to flow into the soil, thereby contaminating the environment.
Another well-known packaging system includes a syringe-like container having two parallel, similarly dimensioned chambers and a plunger extending into each chamber. When the plunger is depressed, approximately equal quantities of resin and hardener are dispensed. Although this system is effective in providing a proper ratio of hardener to resin, the system is relatively expensive, and the actual weight of the package itself (typically made of molded polyethylene) sometimes exceeds that of the epoxy adhesive it contains. Furthermore, after use the package continues to contain some uncured resin and hardener, which makes the used package unsuitable for recycling or for disposal in a landfill.
In both these prior systems, it is necessary for the user to provide a suitable mixing surface as well as the implements needed to mix and apply the epoxy adhesive. This creates a messy work area and often necessitates disposal of the used mixing implements. Additionally, the user can inadvertently touch the pool of mixed adhesive, leading to further mess and inconvenience.